CMP and cleaning

In Preston's equation for CMP removal rate, which quantity is the removal rate proportional to?

  1. AThe color of the slurry
  2. BThe wafer diameter
  3. CThe product of polishing pressure and the relative velocity between pad and wafer
Show answer and explanation

Answer: C. The product of polishing pressure and the relative velocity between pad and wafer

Preston's equation is the empirical relation removal rate = k × pressure × relative velocity, stating that the removal rate is proportional to the product of pressure and velocity. The constant k depends on the slurry, pad and film being polished.

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More CMP and cleaning questions

  1. Which abrasive particles are often used in STI CMP to achieve high polishing selectivity of oxide to silicon nitride?
  2. Which cleaning method applies MHz-range ultrasound to the cleaning solution to remove tiny particles from the wafer surface?
  3. What is the main purpose of cleaning with ozone dissolved in ultrapure water (ozonated water)?
  4. What is the role of benzotriazole (BTA) and similar additives in copper CMP slurries?
  5. What is the role of the retaining ring that surrounds the wafer in a CMP polishing head?